(1) Field of the Invention
The present invention relates to caliper type brakes for bicycles, and more particularly to a caliper type brake which can be operated by a small operating force and in which clearance between a brake rubber and a rim is adjusted by means of a limiting tool and a spanner-attaching tool, both tools being fixed on a through bolt connecting opposite brake blocks.
(2) Description of the Prior Art
A conventional caliper type brake for bicycles is constituted as illustrated in FIGS. 1 and 2. There is shown a brake comprising a left block 1 and a right block 2 which are pivotably connected by a through bolt 3 with washer 4 and 5, and it is driven in opening direction by a return spring 14 arranged along the opposite blocks 1, 2. Referring to FIG. 3, the through bolt 3 consists of bolt portions 9, 9 and a collar 10. The left block 1 and the right block 2 are attached to the bolt portion 9 through a washer 6, a nut 7 and a locknut 8. The through bolt 3 is attached to a bicycle frame (not shown) at the bolt portion 9' through washers 11, 11 and is fixed by a washer 12 and nut 13. The collar 10 is provided with a groove 15 to which the center horizontal portion of the return spring 14 is fitted and supported. Both ends of the return spring 14 are attached respectively to the inside of spring supports 1', 2' connected to the left block 1 and the right block 2 by means of spot welding, so that both blocks 1, 2 are stretched outwards. Ends of the left block 1 and the right block 2 are respectively provided with brake rubbers 16, 16'. A wire clamping screw 17 is attached to the other end of the left block 1; an adjusting screw 19 is attached to the other end of the right block 2 through an attaching tool 18 for adjusting screw. An outer wire 21 of a brake-operating Bowden cable 20 is supported to the upper end of the adjusting screw 19, and an inner wire 22 thereof is fixed by inserting the lower end to the wire clamping screw 17.
After the caliper type brake constituted as above is attached to a bicycle frame, the inner wire 22 is pulled by operating a brake lever (not shown) fixed to a handle and the brake rubbers 16, 16' are pushed to a rim so that the brake action is effected. In this case, the left block 1 and the right block 2 are pivoted inwards against the bending spring force at both ends of the return spring 14, therefore the brake operation is difficult if the spring force of the return spring is too strong. Also when a general-purpose caliper type brake is attached to bicycles for children, the operation is difficult for most children.